Hydroxylation products of dihydropyran derivatives and their hydrogenation to tetrahydroxy alkanes



or ester group The ring carbon atom linked to the hydroxyl-substitutedradical.

HYDRUXYLATTQN PRQDUQTS F- DEHYDRG- PYRAN DEREVATTVE AND THEE? HYDRO-GENATIQN T0 TETRAHYDRGXY ALKANES George B. Payne, Berkeley, Qalih,assignor to Shell Gil Company, New York, N.Y., a corporation of DelawareNo Drawing. Filed Dec. 28, 1961, Ser. No. 162,923

15 tllaims. (Cl. zen-345.7 t

This invention relates to new cyclic ethers having a special structurewhich makes them valuable starting materials for the manufacture ofpolymeric products. The advantageous polymers and other new derivativesof the novel polyhydroxy cyclic ethers are also features of theinvention; p

The new cyclic etherssof the invention are polyhydroxy tetrahydropyranswhich have each of the carbon atoms linked tothe ether oxygen atomsubstituted by a functional group. One of these functional groups is thehydroxyl group and the other is a methylol group (-CH OH) or a carbonylgroup, particularly a formyl carboxyl carbon atoms directly joined tothe ether oxygen is also substituted by a hydroxyl group; ,Thus the newethers have two adjacent carbinol groups linked to the ether oxygenwhich is directly attached to the ring carbon which carries the methylolor carbonyl substituent. In the following more detailed description ofthe invention the methylol, carboxaldehyde and carboxyl-substitutedpolyhydroxy tetrahyropyrans will be discussed separately since each ofthese three types of new compounds has its own special advantages andproperties although all. three types share common structural featureswhich make I 1 them similarly reactive under certain conditions so that.both types can serve for the synthesis of certain similarly usefulderivatives. Especially advantageous new polymer-forming comtedStatesPalate gen are: 2,3-dihydroxtetrahydropyran-o-carboxaldehyde and itsalkyl substitution products such as Examples of new carboxylicacid-substituted dihydroxy t tetrahydropyrans of the invention, :that iscompounds of the preceding formulain which X represents the; carpoundsof the invention are 2,3-dihyroxy-6 carbonyl-substitutedtetrahydropyrans which can be represented by the formula: r

In this formula the KS can be the same of different members of the groupconsisting of hydrogen atoms and lower alkyl radicals. Especiallyadvantageous compounds are those of this formula in which R is hydrogenor an alkyl radical of 1 to 3 carbon atoms, that isa methyl, Y ethyl ornormal or isopropyl radical; X in this formula represents hydrogen or ahydroxyl or hydrocarbyloxy Representative new formyl-substituteddihydroxytetrahydropyrans of this type, that is, compounds of theforegoing formula in which'X represents hydroboxylic acid group(".-COOH) are 2,3-dihydroxytetrahydropyran-6 carboxylic acid;

2,3-dihydroxy-4-methyltetrahydropyran-6-carboxylic acid;

2,3-hydroxy-4,6-diethyltetrahydropyran 6-carboxylic acid;

2,3-dihydroxy-4-methyl-3-normal propyltetrahydropyran-I 6-carboxy'licacid; V 2,3-dihydroxy4,5,6-triisopropyltetiahydropyran-G- carboxylicacid; 2,3-dihydroXy-5,6-dimethyl-3,4 diethyltetrahydropyran-6-carboxylic acid and similar alkyl-substituted2,3-dihydroxytetrahydropyran-6-carboxylic acids.

The esters of theseacids are included in this subgroup of the newcompounds. r The estersof the aliphatic saturated l i and monooelcfinicalcohols of l to 18 carbon atoms are particularly advantageous. a

The new methylol-substituted compounds of the invention which arerepresented by the foregoing structural formula when X represents the CHOH group, are ex emplified by t t 2,3-dihydroxytetradropyran-Gnethanol;I r 2,3-dihydroXy-5methyltetrahydropyran-6-methanol;

2, 3-dihydroxy-4, 5-dimethyltetrahydropyran-6-mcthanol2,3-dihydroxy-3ethyl S-methyltetrahydropyran-6- methanol; 1 K

2,3,-dihydroxy-4-ethyl-3-isopropyltetrahydropyran-6- methanol; V

2,3-dil1ydroxy 3,4,5 triethyltetrahydropyran-6-methanol;

2,3-dihydroxy-6-methyl-4,5-diethyl-3-normalpropyltetrahydropyran-methanol and the like.'

The new compounds can be made conveniently by hydroxylating thecorresponding 3,4-dihydro-l,2-pyrans substituted in the 2 position by 'acarboxaldehyde, carboxylic acid or carboxylic acid ester or methanolgroup. US. Patents 2,479,283 and 2,479,284 describesuitable methods ofmaking dihydropyrans of this type which are advantageous startingmaterials for hydroxylation to the newcompounds of theinventioriii Theforcgoingformylsubstituted dihydroxytetiahydropyrans can be produced byhydroxlating p 3-methyl-3,4-dihydro-1,2-pyran-2-carboxa1dehyde;

2,3-dimethyl-3,4-dihydro-1,2,-pyran-2-carboxaldehyde;

3-ethyl-4-isopropyl'3,4-dihydro-1,2-pyran-2-carboxalde-2,4-diethyl-S-normal propyl-3,4 -dihydro-1,2,-pyran 2-carboxaldehyde andt 2,3,4,S-tetramethyl-3,4-dihydro 1,2-pyran-2- carboxaldehyde,respectively. p Similarly,the carboxylic acid-substituted compoundsgiven as examples above, can be synthesized by hydroxylating3,4-dihydro-l,2pyran2-carboxylic acid; 4-methyl-3,4-dihydro-l,2-pyran-2-carboxylic acid;

Patented Feb. 2, 1965 2,4-diethyl-3,4-dil1yo'ro-1,2-pyran-2-carboxylicacid;

4-methyl-5-normal propyl-3,4-dihydro-l,2-pyran-2- carboxylic acid;2,3,4-triisopropyl-3,4-dihydro-l,2-pyran- ,Z-carboxylic acid and2,3-dimethyl-4,5-diethyl-3,4-dihydro-l,2-

pyran-Z-carboxylic acid respectively while the new ester 7 products aremade by hydroxylatingthe corresponding esters of these acids. 7

Hydroxylation of the following methylol-substituted dihydropyransaffords the respective methylol-substituted dihydroxytetrahydropyransgiven above as examples of this subgroup of the new compounds of theinvention:

3,4-dihydro-1,Z-pyrari-Z-methanolg3-methyl-3,4dihydro-1,2-pyran-2-methanol;

Y 3,4-dimethyl-3,4-dihydro-1,Z-pyran-Z-methanol;

V tungstic acid between about 0.1 and about 10% W. of the dihydropyrancompound being hydroxylated' are suitable,

amounts'between about 1 and about 5% w. being more advantageous. Thereaction is most suitably cit acted at a pH of about 4 to about 6 whichcan be maintained by adding a base to the reaction mixture at anappropriate rate. Sodium or potassium or other alkali metal hydroxide orlime or other alkaline earth metal hydroxide or inorganic carbonatessuch as sodium bicarbonate and the like or other buiiering agents can'beused for control of the pH. Approximately equal molecular amounts ofhydrogen peroxide and dihydropyran compound are useful proportions butan excess of either reactant can be employed and it is generallypreferable to use a small excess of hydrogen peroxide. Aqueous hydrogenperoxide of about 10 toabout 90% concentration can be used butconcentrations in the range of about to about 60% by the order of about10 to about 60 C. can be used, but the best results are usually obtainedat about to about 50C. In this temperature range the hydroxylation isusually sufficiently complete in about 1 to about 5 hours. Any suitablemethod of contacting the reactants in the liquid phase can be employedin carrying out the reaction which can be conducted batchwise,continuously or intermittently. Inert solvents for the reactants can beused as an aid in promotinginterrnittent contact of the reactantsespecially where solid starting dihydropyran compounds are used.However, with liquid reactants a solvent is usually not necessary. Anysuitable method of product recovery can: be used. Solvent extractioncombined with distillation is often useful but it is not essential thatthese new products be recovered as such since they are often useful forfurther reaction Without separation from the mixture in which they areproduced. I

The following examples illustrate in more detail some of the ways inwhich the'new-compounds can be pro duced by hydroxylating thecorresponding dihydropyran compound.

Example I.Pr0dzecti0n of 2,S-llihydroxyzetmhydropyran- 6-carboxaldehydepyran-Z-carboxaldeliyde was added over a period of half an hour. The pHwas held at 4.5 to 5.0 by adding 24- ml. of normal sodium hydroxide overa three hour period.

At that time the reaction was indicated to be 98% complete'by iodometrictitration. Analysis shows production of2,3-dihydroxytetrahyclropyran-2-carboxaldehyde in substantiallyqualitative yield.

Example 1I.-2,3-dilzydr0xy-6-methyltetrahydropyran- 6-cai'b0xala'ehya'eproduction When the process of Example I is carried out using 63 gramsof Z-methyl 3,4 dihydro-1,2-pyran2-carboxaldehyde for the reaction, asimilar good yield of2,3-dihydroxy-6-methyltetrahydropyran-6-carboxaldehyde is obtained.

Example III.2,3-dihydr0xy3,6-dimethylletrahydropyran-6-carboxaldehydeproduction 2,5-dimethyl-SA-dihydro-1,2-pyran 2 carboxaldehyde reactedwith about 10% excess of 30% hydrogen peroxide solution in the apparatusof Example I for about three hours whilemaintaining the pH about 4.5 byperiodic addition of l N sodium hydroxid solution affords-a good yieldof 2,3-dihydroxy-3,6-dirnethylteuahydropyran-os carboxaldehyde.

Example ZV.2,3-dillydroxytetrahydropyran-o-carboxylic acid productionExample V.2,3-dihydr0xy-6-methyltetrahydropyranv d-carboxylz'c acidproduction Using 0.55 mole of'30% hydrogen peroxide for reaction with 71grams (0.50 mole) of 2-methyl-3,4-chhydro- 1,2-pyran-2-carboxylic acidby the method of Example 1.

and maintaining the pH about '5 .0 by addition of normal sodiumhydroxide solution affords2,3-dihydroxy-6-methyltetrahydropyran-6-carboxylic acid sodium salt ingood yield; 7

Example V1.-2,3-dihydr0xy-3,6-dimethylzetrahydropyrano-carboxylz'c acidproduction When half a mole of 2,5-dirnethyl-3,4-dihydro-l,2-pyran-2-carboxylic acid is substituted for the3,4-dihydrol,Z-pyran-Z-oarboxaldehyde in the method of Example I theproduct is 2,3-dihydroxy-3,6-dimcthyltetraliydropyrano-carboxylic acidsodium salt. Example VH.2,3-dihydr0xytetrahydropyrano-nte{harml 7production c Half a mole (57 g.) of 3,4-dihydro-1,2-pyran-2-mefianol wasreacted at 2530 C. by the method of Example I using N sodium hydroxideto maintain the pH above 4.5. After 4 hrs, iodornetric titration showedthat 0.49 mole of peroxide had been consumed. Gnly 9 ml. of alkali hadbeen consumed. Product Was 2,3-dihydroxytctrahydropyran-2-methanol ingood yield. Example VIII.-2,3-dihydr0xy-6-m2thyltetrahydropyrau-6-metlmn0l production The method of Example Vll using an equal molecularamount of 2-methyl-3,4-dihydro-i,2-pyran-2-methanol in place of the3,4-dihydro-LZ-pyran-Z-methanol affords a good yield of 2,3dihydroxy-6-methyltetrahydropyran- 6-methanol.

Example IX.-2,3-dfl1ydr0xy-3,6-dimethylietrahydropyran-d-mcthanolproduction 2,S-dimethyl-S,4-dihydro-1,2-pyran-2methanol reacted by theprocess of Example I with about 10% excess of 30% hydrogen peroxide atabout 35 C. for three hours while maintaining a pH of about 5.0 byadding sodium hydroxide solution (1 N) as required, affords2,3-dihydroxy-3,6-dimethyltetrahydropyran-e-methanol in good yield.

Using the method of the foregoing examples S-methyl-3,4-dihydro-l,Z-pyran-Z-carboxaldehyde can be similarly hydroxylated toobtain 2,3-dihydroxy-3-methyl-tetrahydropyran-G-oarboxaldehydc; 3,4dimethyl 3,4-dihydro-l,2- pyran-Z-carboxaldehyde can be hydroxylated to2,3-dihydroxy-4,S-dimethyltetrahydropyran 6-carboxaldehyde and2,3,5-trirnethyl-3,4-dihydro-1,2-pyran-2-carboxaldehyde can be convertedto 2,3-dil1ydroxy-3,5,6-tuimethyltetrahydropyran-fi-carboxaldehyde. Inthe same way 2,3- dihydrxy-3-ethyltetrahydropyran--carboxylic acid isproduced from 5-ethyl-3,4-dihydro-l,2-pyran-2-carboxylic acid;2,3-dihydroxy-3,S-dimethyltetrahydropyran-o carboxylic acid is producedfrom 3,5-dimethyl-3,4-dihydro- 1,2-pyran-2-carboxylic acid and2,3-dihydroxy-3,4-dimethyl-5-ethyltetrahydropyran-dcarboxylic acid isobtained by hydroxylating 4,5-dimethyl-3-etl1yl-3,4-dihydro-1,2-pyran-2-carboxylic acid.

The ethyl ester of 3,4-dihydro-1,2-pyran-2-carboxylic acid affords theethyl ester of 2,3-dihydroxytetrahydropyran--oarboxylic acid under theconditions of Example I while the methyl ester of2,4-dimethyl-3,4-dihydro1,2- pyran-Z-carboxylic acid yields the methylester of 2,3-dihydroxy-4,o-dimethyltetrahydropyran 6 carboxylic acid andthe isopropl ester of 2,3,4-trimethyl-3,4-dihydro-1,2-pyran-Z-carboxylic acid yields the isopropyl ester of 2,3-dihydroxyl,5,6-trimethyltetrahydropyran 6 carboxylic acid under likeconditions.

From 4,5-dimethyl-3,4-dihydro-1,2-pyran-2-methanol a good yield of2,3-dihydroxy-3,4-dimethyltetrahydropyran- -methanol is obtained andfrom 2,4,5-trimethyl-3,4-dihydro-l,2-pyr-an-2-methanol and3,4,5-trimethyl-3,4-dihydro-1,2-pyran-2-methanol one obtains2,3-dihydroxy- 3,4,6-trimethyltetrahydropyran-G-methanol and2,3-dihydroxy-3,4,5 trimethyltetrahydropyran-fi-methanol, respectivcly,under similar conditions.

Other methods of manufacturing the new compounds are available. The2,3-dihydroxytetrahydropyran-6-carboxylic acids can be made by oxidizingthe corresponding new aldehydes which can also be reduced byhydrogenation or reaction with lithium hydride or an aluminum alcoholateor the like to make the new 2,3-dihydr0xytetrahydropyran fi-methanols.

As previously pointed out these new compounds are advantageous startingmaterials for the manufacture of polymeric materials having valuableproperties. Both homopolymers and copolymers can be produced. Thermalpolymerization of the new2,3-dihydroxy-tetrahydropyran-Z-carboxaldehydes, for example, yieldspolymeric cyclic hemi-acetals according to the equation: i

In this equation R represents hydrogen or a lower alkyl group aspreviously described and x is a number representing the degree ofpolymerization which will depend upon the polymerization conditions usedbut will usually be at least about 6 and more advantageously about 20 orhigher. Heating at about 50 C. to about 100 C. for about 10 minutes toan hour or more is usually sufiicient but higher temperatures and longertimes can be used to promote higher degrees of polymerization. Thepolymerization. The polymerization can be carried out in bulk or insolution in suitable solvents such as water or aqueous or anhydrousacetone, chloroform or the like. Depending upon the degree ofpolymerization achieved, the products are liquids or high molecularweight solids which will have various degrees of solubility inconventional solvents such as benzene, toluene, acetone, and the like.The higher molecular Weight polymers can be utilized in many importantapplications with or without cross linking of the polymer chains throughthe free hydroxyl groups. Suitable cross linking agents are, forinstance, polycarboxa ylic acids such as maleic acid, terephthalic acidand the like, or polyisocyanates such as toluene diisocyanates, durenediisocyanate, etc. Satisfactory cures can usually be obtained with about0.1 to about ten mole percent of cross linking agent based on the amountof 2,3-dihydroxytetrahydropyran-Z-carboxaldehyde initially employed. Thecross linking agent is advantageously added after at least partialpolymerization of the starting2,3-dihydroxytetrahydropyran-Z-carboxaldehyde. The products can be,pressed or molded into various plastic articles and, depending on theirsolubility, can be used in surface coating and impregnating compositionswhich can be applied in molten form or in solution.

The 2,3-dihydroxytetrahydropyran-6-carboxylic acids can be polymerizedby heating, preferably in the presence of an acid-acting catalyst, toform polymers with ester and hemi-acetal linkages in accordance with theequation:

where the Rs and X have the same significance as in the previousequation. The polymerization is most advantageously carried out at aboutto about C. with simultaneous removals of the water formed in theesterification. This can be accomplished by distillation, for instancewith an azeotroping agent such as toluene or the like. Suitablecatalysts are sulfuric, phosphoric and like acids which are effective invery small amounts ofthe order of about 0.02 to 0.5% W. for example.These polymers can be applied in molding or surface coating with orwithout crosslinking through the hydroxyl group of the hemiacetallinkage as described above in connection with the newdihydroxytetrahydropyran-6-carboxaldehydes.

Where esters of the 2,3-dihydroxytetrahydropyran-S- carboxylic acids areused as starting materials for the polymers, the products prepared inthe same way will be linear poly-hemiacetals having the ester groups asside chains as shown in the following equation:

Here R and x have the significance previously indicated and R representsthe radio 1 of the alcohol which was used in making the starting ester.Particularly advantageous starting esters for this application are thosefrom unsaturated alcohols such as allyl, methallyl and the hypotheticalvinyl alcohol since the resulting polymers canbe cross linked byperoxide-catalyzed polymerization of the unsaturated alcohol groups.With esters of unsaturated alcohols such as, for instance, thealkylesters of l to 4 carbon atoms, the cross linking can be effected byreaction of the free hydroxyl groups with polycarboxylic carbonylicacids or polyisocyanates as previously described. All these areapplicable for molding and surface coating in the same way as those madefrom the corresponding 2,3- dihydroxytetrahydropyran-S-carboxylic acids.

The polymerization of the new 2,3-dihydroxytetrahydropyran-6-methanolscan be carried out as above de scribed for the corresponding estercompounds. The linear hemiacetal products will have methylol groups inplace of the ester groups on the chain and these can take amass r '2?part in cross linking in the same way as the other free hydroxyl groupsaffording polymers of analogous properties.

The polymers of the present invention can be utilized for a variety ofdifferent applications. They can be pressed into attractive plasticmoldings or formed into sheets, films or funicular structures such asbristles, filaments and other articles commonly made with syntheticresins. They can be used by themselves in these applications or they canbe combined with various plasticizing materials, such as esters, asdioctyl phthalate, tricresyl phosphate, l,'5-pentanediol dipropionate,hexanetriol tr"- acetate, polyethylene glycols, polypropylene glycols,glycerol, hexanetriol, glycerol tributyl ether and the like, andmixtures thereof.

The new polymers can also be blended or otherwise combined with otherpolymers and resins or tars and pitches. They can be combined, forexample, with epoxy resins, polyurethane resins, polyamide,urea-formaldehyde and phenol resins, polythiopolymercaptans, vinylresins, coal tar, asphalt, middle oil, coal tar pitch, and the like, invarious proportions. Such blending can be used to improve stability,workability or extend commercial applications.

The new polymers of the invention having the necessary solubility insolvents can be utilized in the formation of Surface coatingcompositions and impregnating compositions or for the treatment ofcloth, paper and the like.

The new compounds are also useful for the synthesis of other valuablederivatives. The esters of the 2,3-dihydroxytetrahydropyran-o-carboxylic acids are particularly useful. Forexample, the methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, andsimilar esters are of value as special solvents, etc. The higher fattyacid esters of the present dihydropyran methanols, such as the stearates, the oleates, the palmitatcs, and other esters of fatty acidscontaining from to 18 carbon atoms, are of value as plasticizers,lubricants in molding compositions and the like. Unsaturated esters ofthe present novel carboxylic acids, such as the allyl, the methallyl,the crotyl, and homologous or analogous esters containing at least oneolefinic bond in the molecule, are useful as polymerizable materialsadapted to peroxide'catalyzed polymerization either alone or with otherpolymerizable compounds such as compounds containing reactive ethylenicbonds. The carboxylic acids of the present invention also find efiectiveutility as basis for the preparation of derived amides, acid halides,and similar compounds.

The metal and other salts of the present carboxylic acids may beprepared advantageously as by suitable reaction of the free acid with abase, or by reaction leading to cation exchange converting the salt ofone metal to the salt of another. The alkali metal salts such as sodium,potassium, lithium, etc., the ammonium salt, the alkaline earth metalsalts as cesium, magnesium, calcium, and rubidium, and other metal saltssuch as the lead, copper, mercury, silver, barium, cadmium, chromium,cobalt, iron, nickel, aluminum, manganese, and similar salts thus areprovided. The copper and similar salts of toxic metals are of particularvalue as components of insecticidal and fungicidal compositions, etc.The cobalt, manganese, and similar salts are of value as driers in paintcompositions, and the like.

Hydrogenation of the new 2,3-dihydrox-6-carbonylsubstitutedtetrahydropyrans to obtain polyols which have many applications is aspecial feature of the invention. A. typical method of hydrogenation isillustrated in the following example:

Example X.-1,2,5,6-l2exanetetr0i production 2,3 dihydroxytetrahydropyrano-methanol was prepared as in Example VII and the aqueous hydroxylationmixture was transferred to an autoclave without isolating the product.One teaspoonful of Raney nickel hydrogenation catalyst was added and themixture was hydrogenated at 60 C. and 750 pounds hydrogen pressure.After 3 hours, the temperature was raised to 80 C. for another 2 hours.Absorption of hydrogen was finally very slow at the point where 85% ofthe theoretical amount had been consumed. The autoclave was cooled,vented, and the catalyst (pyrophoric) removed by filtration. Afterconcentration to a residue, the latter (39 g.) was recrystallized fromethanol-ethyl acetate at 20 C. to give 17 g. yield) of crude 1,25,6-hexanetetrol, M.P. 6065 C. Recrystallization from ethanol-acetone gave 7g., MP. 90 93 C. Recrystallization of this from ml. of ethanol-acetone(1:1) gave 5.1 -g., Ml 9495 C. A final crystallization was carried outat room temperature to give 4.2 g. of pure l,2,5,6- hexanetetrol, NP.96-965 C.

The same tetrol of 90% purity (by titration of vicinal hydroxyls) wasobtained by hydrogenating in the same way 2,3dihydroxytetrahydropyran-6-carboxaldehyde produced as in Example I. Thistetrol analyzed as fol- In large scale production ofl,2,5,6-hexanetetrol a 22- liter glass flask was equipped with astirrer, thermometer, two dropping funnels an pH measuring electrodes.The flask was charged with 10 liters of distilled water, 66 grams oftungstic acid and 2060 grams (18.2 moles) of 30% aqueous hydrogenperoxide. The mixture was stirred and the addition of 1860 grams (16.6moles) of freshly distilled 3,4-dihydro-l,2-pyran-2-carboxaldehyde wasstarted. Simultaneously, a slow stream of l N NaOH was added to thereactants and this rate adjusted so as to maintain a pH of 4-.55.0. Theaddition was completed in 3 hours and required ice cooling in order tokeep the reaction temperature at 25-30 C.

The product from two such runs was hydrogenated using Raney nickelcatalyst as C. and 750 p.s.i.g. hydrogen pressure, after which thehydrogenated crude was concentrated to a solid residue at C. and 20 mm.Hg absolute. Recrystallization of the residue from ethanol-ethyl acetateat 20 C. gave 1830 grams of crude 1,2,5,6-hexanetetrol, Ml. 83-106" C.The yield based on 3,4-dihydro-l,2-pyran-2-carboxaldehyde charged was37% in.

When 2,3-dihydroxytetrahydropyran-6-carboxylic acid from the method ofExample IV is hydrogenated under the same conditions the product is2,5,6-tril1ydroxyhexanoic acid.

Instead of Raney nickel, other hydrogenation catalysts can be used incarrying out this simultaneous ring opening and hydrogenation to obtainthe tetrol products. Generally speaking, metal hydrogenation catalystssuch as platinum, palladium, ruthenium, tungsten, vanadium, iron,cobalt, nickel, chromia, molybdenum and the like or mixtures thereof ortheir oxides or sulfides etc. can be used. Copper chromite is oneexample of a suitable compound hydrogenation catalyst. The catalyst maybe employed in finely divided form and dispersed in the reaction mixtureor it can be used in a more massive state either with or without asupport such as pumice, diatomaceous earth, clay, alumina, carbon, orthe like the reactants contacted therewith by flowing the liquid mixturethrough a bed of the catalyst or other known hydrogenation methods canbe used.

The temperature which will be most advantageous will vary with theactivity of the chosen catalyst but will usually be in the range ofabout 30 to about 250 C., but in any case below the pyrolysistemperature of the feed and as a rule, preferably below about 150 C.Hydrogen pressures greater than atmospheric are advantageous and aconvenient range of pressure is about 250 to about 10,000 pounds persquare inch. Under these conditions the reaction can usually becompleted in about one half to about 20 hours when using 0.05% or moreof catalyst based on the weight of reaction mixture.

The polyols produced in the foregoing way can be reacted withalpha-beta-monoethylenic aldehydes having a 10methyltetrahydropyran-6-carboxaldehyde of Example III:Z-vinyl-5,7a-dimethyl--formyl-1,3 dioxolo[4,5-6]tetrahydropyran;

The acrolein cyclic acetal of the2,3-dihydroxytetrahydropyran-6-carboxylic acid of Example IV:2-vinyl-l,3- dioxolo [4,5 -6] tetrahydropyran-S -carboxylic acid;

The methacrolein cyclic acetal of the n-butyl ester of the acid ofExample IV: butyl 2-isopropenyl-1,3-dioxolo-[4,5-6]tetrahydropyran-S-carboxylate;

terminal methylene group, such as acrolein or methacro- The acroleincyclic acetal of 2,3-dihydroxy-6-methyllein, etc., to produce 2-vinyldioxolane compounds which tetrahydropyran-6-carboxylic acid of ExampleV: 2-vinylare particularly valuable in the formulation of air-dryingS-methyl-1,3-dioxolo[4,5-61tetrahydropyran-5 carboxylio surface coatingcompositions. The bisacrolein acetal of acid; l,2,5,6-hexanetetrol isdirectly useful in this way. The The methacrolein cyclic acetal of the2-ethylhexylester acrolein acetal of 2,5,6-trihydroxyhexanoic acid orits 5 of 2,3-dihydroxy-3,6-dimethyltetrahydropyran-6-carboxylesters arepreferably used for this purpose in combination ic acid of Example VI:Lethylhexyl-Z-isopropenyl-5,7awith a compound having a plurality of2-vinyl-l,3-cyclic dirnethyl-l,3-dioxide[4,5-6]tetrahydropyran 5carboxylacetal radicals in the molecule or is reacted with itself ate;or more preferably with a diol such as ethylene glycol or The acroleincyclic acetal of 2,3-dihydroXy-6-methyldior tri-ethyleneglycol underesterification conditions so dropyran-G-methanol of Example VII:2-Vinyl-l,3-dioxoloas to join together two molecules. The linking isprefer- [4.5-6]tetrahydropyran-S-methanol; ably carried out as atransesterification according to the The methacrolein cyclic acetal ofthe 2,.i-dihydroxyillustrative equations:6-metl1yltetrahydropyran-fi-methanol of Example VIII: 2-

OR on 0 0:5 c on CH;,(|3HCH -CH;&H-&OR I'I2 CHCH2 CH2 H-OrCHCH2CHz-CHCH3HOR' (I) 6 CH CH \c I HO-OHz-CH2-OH A) fiH OH H OIIg Hfl 112 on on (I)H-filHCH CHz-0HCOCHz-OH O--l-(5LE[CH -CH CH-CH ZHOR' o\ /0 CH O a. 51;

Here R is the radical of a lower alkanol. Alkyl orthotitanates areadvantageous catalysts for carrying out the ester exchange withoutopening the acetal rings.

Another special feature of the invention is the cyclic acetalderivatives of the hereinbefore-described new 2,3-dihydroxytetrahydropyran aldehydes, carboxylic acids and esters, andmethylol compounds. The acetal group of these new products is derivedfrom alpha,beta-monoethylenic aldehydes having a terminal methylenegroup such as acrolein methacrolein, alpha-ethylacrolein and the like.One important type of these new compounds has the general structuralformula:

vinyl-S-methyl- 1, 3-dioxolo [4,5 -6] tetrahydropyran-S -methanol, and

The alpha-ethyl acrolein cyclic acetal of the2,3-dihydroxy-3,6-methyltetrahydropyran-6-rnethanol of Example IX:2-isopropenyl-5,7a-dimethyl-1,3 dioxolo [4,5-6]tetrahydropyran-S-methanol.

These and the related cyclic acetals of 2,3-dihydroxytetrahydropyrans ofthe foregoing general. formula can be used advantageously with thepreviously described compounds having a plurality of 2-vinyl-1,3-cyclicacetal radicals per molecule in making air-drying surface coatingcompositions. Mixtures of these cyclic acetals of2,3-dihydroxytetrahydropyran compounds with the bis-acrolein and/ orbismethacrolein acetal of 1,2,5,6-hexanetetraol are especially usefulfor this purpose.

In making air-drying surface-coating compositions of this general typeone can also use as the component or components having a plurality of2-vinyl-1,3-cyclic acetal radicals in the molecule, the productsobtainable by linking together a plurality of molecules of the foregoingcyclic acetals of the 2,3-dihydroxy-tetrahydropyran compounds or bylinking together a plurality of the new 2,3- dihydroxytetrahydropyrancompounds and reacting the product with an alpha,beta-monoethylenicaldehyde having a terminal methylene group to introduce the requiredplurality of 2-vinyl-l,3-cyclic acetal radicals. Thus, for example, the2,3-dihydroxytetrahydropyran-6-carboxaldehydes of Examples I, II, andIII, individually or as mix tures of tWo or all three of thesealdehydes, can be subjected to Tishchenko reaction in the presence of analuminum alkoxide. For instance, about 0.1 to about 5 mole percent ofaluminum triisopropoxide based on the 1 ll amount of aldehyde presentcan be used at about 16 to about 50 C. employing isopropanol as solvent.The product ester can then be converted to the bis-cyclic acetal underthe acetal-forming conditions previously described, the reaction takingplace according to the equation:

The same compounds can be obtained by similar Tishchenko reaction of thecyclic acetals of the 2,3-dihydroxytetrahydropyran-6-carboxaldehydcs orby esterification of the cyclic acetals of the2,3-dihydroxytetrahydropyran-6-carboxylic acids of Examples IV, V and VIor like acids with the cyclic acetals of2,3-dihydroxytetrahydropyran-o-methanols such as those of Examples VII,VIII, and IX. Instead of the carboxylic acids one can use their estersof lower aliphatic monohydric alcohols as starting materials and conductthe reaction as an alcohol exchange in which the lower alcohol isremoved from the mixture as fast as it is form-ed. In these ways one canobtain:

2-vinyl-1, 3-dioxolo [4,5 -b] -5 -tetrahydropyranylmethyl-Z- vinyll 3-dioxolo [4,5 -b] tetrahydropyran-S -carboxyl ate 2-vinyl- 1,3-dioxolo[4,5 -b] -5 -methyl-5 -tetrahydropyranylmethyl-Z-vinyl-l ,3 -dioxolo[4,5 -b -5 -methyltetrahydropyran-S -carboxyl ate Z-isopropenyll,3-dioxolo [4,5 -b] -5 ,7 a-dimethyl-S -tetrahydropyranylrnethyl 2isopropenyll ,3 -dioxolo [4,5- b]-5,7a-dimethyltetrahydropyran-S-carboxylate Z-isopropenyl-l S-dioxolo[4,5-b] -5,7a-dirnethyl-S-tetrahydropyranylmethyl-2-vinyl-1,3-dioxolo[4,5-b1tetrahydropyran-S-carboxylateZ-isopropenyl-1,3-dioxolo[4,5-b]-6,7-dimethyl-5-tetrahydromethyl-Q-vinyl-l,3-dioxolo6,7-dimethyltetrahydropyranfi-carboxylateInstead of direct linking of the new 2,3-dihydroxytetrahydropyrancompounds in the foregoing ways, these compounds or the previouslydescribed cyclic acetals can be linked by means or a polyfunctionalcompound reactive with the formyl, carboxylic acid, carboxylic acidester or methanol group which they contain. For instance, the 2,3dihydroxytetrahydropyran 6 carboxaldehydes can be reacted with adialdehyde such as glutaraldehyde under aldol condensation conditions.vThe 2,3-dihydr oxytetrahydropyran-6-carboxylic acids or their esterscan, for example, be reacted with a polyol such as ethylene glycol,glycerol or 1,2,6-hexanetriol or the like to obtain polyesters, and the2,3-dihydroxytetrahydropyran-6-methanols can be esterified withpolycarboxylic acids such as oxalic, maleric, malonic, tartaric,phthalic and like acids to link together a plurality of moleculesthrough the methylol group. Due to the tendency of the ring hydroxylgroups to undergo esterification at the same time, it is usuallyadvantageous to convert the 2,3-dihydroxytetrahydropyran--carboxylicacid or ester or methanol to its cyclic acetal before carrying out theesterification reaction which should be conducted under carefullycontrolled conditions at which opening of the cyclic acetal rings isavoided. One suitable method is ester exchange between the starting2,3-dihydroxytetrahydropyran-o-carboxylic acid or ester and an ester ofthe polyol to be used as linking agent, for instance ethyleneglycoldiacetate, or between the 2,3-dihydroxytetrahydropyran 6 methanol and apolyester of the linking polycarboxylic acid, for example diethylfumarate or dimethyl phthalate or the like. Catalysts for the esterexchange are alkali metal alkoxides such for instance as sodiummethoxide or tetraalkyl titanates of which tetraisopropyl and tetrabutyltitanates are typical examples. The reaction is preferably conductedunder anhydrous conditions with continuous removal of the liberatedlower boiling carboxylic acid or alcohol. Distillation with an agentwhich forms a lower boiling azeotrope with the liberated acid or alcoholis one advantageous method of carrying out the ester exchange. Thus, onecan reflux with toluene or the like and take oil toluene-methanol binaryazeotrope when carrying out the exchange with dimethylphthalate or thetoluene-acetic acid binary when exchanging with ethylene glycoldiaoetate. The reaction can usually be completed in about one to fivehours. Examples of the esters obtainable in good yields in .this wayare:

(1 Bis (Z-vinyl- 1 ,3-di0xolo [4,5 -b] -5-tetrahydropyranylmethyl)terephthalate.

(2) Bis- Z-isopropenyl-S-methyl- 1 ,3-dioxolo[4,5-b] -5-tetrahydropyranylmethyl) maleate.

(3 Ethylenebis- 2-vinyl- 1, 3-d1ioxolo[4,5-b] tetrahydropyran-Scarboxylate) (4) 1,4-but-2-enylenebis (Z-vinyl-l ,3-dioxolo [4,5 -b]tetrahydropyran-S-carboxylate) With these and similar polyesters takenindividually or as mixtures, either alone or preferably with one or morecompounds having a single 2-vinyl-l,3-cyclic acetal in the molecule,most advantageously one or more of the previously described new acetalsof 2,3-dihydroxytetrahydropyran-6-carboxaldehydes or -6-carboxylicacids, or -6- carboxylic acid esters or -6inethanols, surface coatingcompositions can be prepared. Air-drying compositions are obtained byincorporating in the mixture a metallic drier compound of the kindwidely used to impart airdrying properties to drying oil-containingpaints, varnishes and enamels. Suitable compounds of cobalt, lead,manganese, copper and like metals are advantageous, particularly assoluble soaps, salts and the like, especially the oleates, nephthenates,resinates, etc. The amount of drier compound which will be most suitablewill vary with the kind of metal and the particular monoand polyacetalderivatives of the starting 2,3-dihydroxytetrahydropyran compound orcompounds chosen, the air temperature employed and the drying speeddesired. Generally amounts of metal in the drier of the order of about0.0005% to about 3% based on the weight of organic film-forming materialin the composition are suitable. The proportion of monoto poly-cyclicacetal compound or compounds in the mixture will ordinarily be about 10to about 60% of monoto about to about 40% w. of poly-.

These new air-drying film-forming compositions can be used with orwithout volatile organic solvents such as petroleum fractions, benzene,acetone, amyl alcohol and the like and their mixtures. Where the liquidmixtures have viscosities which make them suitable for application byspraying or brushing, they are preferably used without added solvent,however. They can be applied as clear coatings or can be mixed withpigments or any of the other ingredients usually used in surface-coatingcompositions including any other suitable film forming resins or oils,etc.

I claim as my invention:

1. A polyhydroxycyclie ether-substituted, aldehyde'of V aqueoushydroxylation mixture without isolating the hyusing Raney nickel ascatalyst and a hydrogen pressure of, about 250 to 1000 p.s.i.g. usingthe catalyst-containing droxylation product. i

11; A method for producing 1,2,5,6-herranetetro1 which i compriseshydroxylating 3,4-dihydro-L2 pyran 2 carwherein each R represents amember of the group consisting of hydrogen and lower alkyl.

2. A polyhydroxycyclic ether-substituted formic acid of the formulawherein each R repres'ents a member of the group consisting of hydrogenand lower alkyl.

3. A polyhydroxycyclic ether-substituted formate of the formula whereineach R represents a member of the group consisting ofhydrogen and loweralkyl and R is a member of the group consisting of aliphatic saturatedhydrocarbon of. 1 to 18 carbon atoms and aliphatic mono-olefinichydrocarbon of 1 to 18 carbon atoms.

4. A polyhydroxycyclic ether-substituted methanol of the formula 0 OHrOHwherein each R represents a member of the group consisting of hydrogenand lower alkyl. i

5. 2,3rdihydroxytetrahydropyran-6-carboxaldehyde. 6.2,3-dihydroxytetrahydropyra -6-carboxylic acid.

7. Lower alkyl ester of 2,3-dihydroxytetrahydropyran- 6-carboxylic acid.

v hydroxylation is effected by reaction with H20 at about boxaldehyde byreaction with H 0 in the presence of tungstic acid catalyst andhydrogenating the hydroxylation product by reaction with hydrogen atabout to about.

250 C. in the presence of a hydrogenation catalyst.

12. A process for producing a tetra-hydroxy alkane having a pair ofdirectly connected carbinol groups linked by a dimethylene chaintoanother pair of directly connected carbinol groups by reaction withhydrogen peroxide which comprises hydroxylating 3,4-dihydro-L2-pyran-2-methanol having attached to the ring only said methanol group andlower alkyl groups and hydrogenating the hydroxylation product byreaction with hydrogen at about divided metal hydrogenation catalyst.

3 to about 250 C. in the presence of a hydrogenation catalyst. 13. Amethod for producing 1,2,5,6-hexanetetro1 which comprises hydroxylating3,4-dihydro-1,2 pyran-2-methanol by reaction with H 0 in the presence 0ttungstic acid catalyst and hydrogenating the aqueous tungsticcatalystcontaining hydroxylation product in the liquid phase by reactionwith hydrogen in the drogenation catalyst. t

14. A process for producing a tetra-hydroxy alkane which compriseshydrogenating at about 30 to about 250 Cpand about 250rto about 10,000p.s.i. hydrogen in i i the presence of a metal catalyst for thehydrogenation, the aqueous catalyst-containing solution of2,3-dihydroxytetrahydropyran-6-methylol havingattached tothe ring onlysaid methylol and members or" the group consisting of hydrogen and loweralkyl obtained by. hydroxylating the corresponding3,-4-dihydyro-1,2-pyran-2 methyl01 at about 10 to about 60 C. usingtungstic acid catalyst.

15. A process for producing tetra-hydroxy susbtituted alklane whichcomprises hydrogenating an aqueous solu- 1 1 tion of 2,3-dihydroxytetrahydropyran 6 carboxaldehyde at about 30 to below about l50 C. usinga hydrogen pressure of about 250 to about 10,000 p.s.i. and a finelyReferences Cited in the. file of this patent UNITED STATES- PATENTS2,479,283 Whetstone Aug 16, 1949 2,514,172 Whetstone et al July 4, 19502,562,848 Whetstone July 31, 1951 2,658,081 Emerson et al. Nov. 3, 1953'2,694,077 7 Guest et a1; Nov. 9, 1954 2,831,000: Buckley et al. Apr. 15,1958 EoaEtoN PATENTS OTHER REFERENCES Petersen: Journal Am. Pharm.Assoc. Sci. Ed., vol. 49, pp. 750455 (1960).

Francis et al.: Canadian Journal of Chemistry, vol. 37, pp. 972-978(1959).

rRvrNo MARCUS, Primary Examiner. I NICHOLAS s. RIZZO, Examiner.

10 .to about 60 iri the' presence of tungsticacid catalyst whilemaintaining-the pH about 4 to about 6 and the hydrogenationis conductedat about 50 to about C.

presence of a metal hy- Netherlands July 15, 1953

1. A POLYHYDROXYCYCLIC ETHER-SUBSTITUTED ALDEHYDE OF THE FORMULA
 2. APOLYHYDROXYCYCLIC ETHER-SUBSTITUTED FORMIC ACID OF THE FORMULA
 3. APOLYHYDROXYCYCLIC ETHER-SUBSTITUTED FORMATE OF THE FORMULA
 4. APOLYHYDROXYCYCLIC ETHER-SUBSTITUTED METHANOL OF THE FORMULA
 9. A PROCESSFOR PRODUCING A TETRA-HYDROXY SUBSTITUTED ALKANE WHICH COMPRISESHYDROXYLATING 3,4-DIHYDRO-1,2PYRAN-2-CARBOXYALDEHYDE HAVING ATTACHED TOTHE RING ONLY SAID FORMYL GROUP AND MEMBERS OF THE GROUP CONSISTING OFHYDROGEN AND LOWER ALKYL GROUPS BY REACTION WITH HYDROGEN PEROXIDE ANDHYDROGENATING THE HYDROXYLATION PRODUCT BY REACTION WITH HYDROGEN ATABOUT 30* TO ABOUT 250*C. IN THE PRESENCE OF A HYDROGENATION CATALYST.